Re: BOOTP/DHCP packets minimum size
- From: Dan Williams <dcbw redhat com>
- To: Bill Moss <bmoss clemson edu>
- Cc: networkmanager list <networkmanager-list gnome org>
- Subject: Re: BOOTP/DHCP packets minimum size
- Date: Sat, 12 Feb 2005 16:16:08 -0500 (EST)
On Sat, 12 Feb 2005, Bill Moss wrote:
> DHCP relayer would (correctly) refuse too short DHCP packets*
> *Issue:* According to the BOOTP and DHCP RFCs, all BOOTP/DHCP packets
> must be at least 300 bytes in size, and use padding to reach this size
> if the actual data is shorter. The DHCP relayer used to verify this size
> and drop packets
> *Problem:* Some DHCP clients/servers (notably, the Windows 2000 DHCP
> server) violate the RFCs and send packets shorter than 300 bytes.
> *Results:* Misbehaving clients would be unable to aquire DHCP leases
> through the DHCP relayer. Misbehaving servers would be unable to hand
> out DHCP leases through the DHCP relayer.
> This means that the buildmsg.c patch should have the value of PAD_STOP
> set to a minimum value of 300. This parameter is controlling the size of
> the DHCP/BOOTP packet. Otherwise, there is a danger that firewalls, and
> routers configured as DHCP relay agents, may drop the dhcp messages as
> invalid. Some DHCP servers may refuse to respong to a discover or
> request that violates this rule.
Thanks for that reference. I will commit the patch I sent you, with the
PAD_STOP adjusted to be 300.
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